bccf4bbfbd
## Summary
This PR adds a new `@tailwindcss/webpack` package that provides a
dedicated webpack loader for Tailwind CSS v4. This loader works with
both standard webpack and Turbopack's webpack loader compatibility
layer.
### Why a dedicated loader?
The current webpack integration uses `postcss-loader` +
`@tailwindcss/postcss`. While this works, a dedicated loader:
- **Eliminates PostCSS as a middleman** - works directly with CSS
strings (no AST conversions)
- **Simpler and more efficient** - follows the same pattern as
`@tailwindcss/vite`
- **Better for Turbopack** - gives direct control over dependency
reporting via webpack's loader API
### How it works
The loader mirrors the Vite plugin's approach:
1. Uses `compile()` from `@tailwindcss/node` to parse CSS and resolve
`@apply` directives
2. Uses `Scanner` from `@tailwindcss/oxide` to scan content files for
utility candidates
3. Reports dependencies via `this.addDependency()` and
`this.addContextDependency()`
4. Optionally optimizes output with Lightning CSS
### Usage
```javascript
// webpack.config.js
module.exports = {
module: {
rules: [
{
test: /.css$/i,
use: [
MiniCssExtractPlugin.loader,
'css-loader',
'@tailwindcss/webpack', // No PostCSS needed!
],
},
],
},
}
```
### Options
- `base` - The base directory to scan for class candidates (defaults to
`process.cwd()`)
- `optimize` - Whether to optimize/minify the output CSS (defaults to
`true` in production)
### Files added
- `packages/@tailwindcss-webpack/` - New package
- `src/index.ts` - Main loader implementation
- `src/index.cts` - CommonJS entry point for webpack compatibility
- `package.json`, `tsconfig.json`, `tsup.config.ts`, `README.md`
- `integrations/webpack/loader.test.ts` - Integration tests
- `integrations/utils.ts` - Added webpack override for transitive
dependencies
### Test plan
- [x] Build test - verifies basic compilation
- [x] Watch test - verifies HMR when adding new Tailwind classes
- [x] `@apply` test - verifies `@apply` directives work correctly
- [x] Optimization test - verifies minification works
---------
Co-authored-by: Robin Malfait <malfait.robin@gmail.com>
420 lines
10 KiB
TypeScript
420 lines
10 KiB
TypeScript
import { css, html, js, json, test } from '../utils'
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test(
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'@tailwindcss/webpack loader (build)',
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{
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fs: {
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'package.json': json`
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{
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"main": "./src/index.js",
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"browser": "./src/index.js",
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"dependencies": {
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"css-loader": "^6",
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"webpack": "^5",
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"webpack-cli": "^5",
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"mini-css-extract-plugin": "^2",
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"tailwindcss": "workspace:^",
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"@tailwindcss/webpack": "workspace:^"
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}
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}
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`,
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'webpack.config.js': js`
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let MiniCssExtractPlugin = require('mini-css-extract-plugin')
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module.exports = {
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output: {
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clean: true,
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},
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plugins: [new MiniCssExtractPlugin()],
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module: {
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rules: [
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{
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test: /.css$/i,
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use: [MiniCssExtractPlugin.loader, 'css-loader', '@tailwindcss/webpack'],
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},
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],
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},
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}
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`,
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'src/index.js': js`import './index.css'`,
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'src/index.html': html`
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<div class="flex"></div>
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`,
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'src/index.css': css`
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@import 'tailwindcss/theme';
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@import 'tailwindcss/utilities';
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`,
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},
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},
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async ({ fs, exec, expect }) => {
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await exec('pnpm webpack --mode=development')
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expect(await fs.dumpFiles('./dist/*.css')).toMatchInlineSnapshot(`
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"
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--- ./dist/main.css ---
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.flex {
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display: flex;
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}
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"
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`)
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},
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)
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test(
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'@tailwindcss/webpack loader (watch)',
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{
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fs: {
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'package.json': json`
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{
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"main": "./src/index.js",
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"browser": "./src/index.js",
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"dependencies": {
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"css-loader": "^6",
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"webpack": "^5",
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"webpack-cli": "^5",
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"mini-css-extract-plugin": "^2",
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"tailwindcss": "workspace:^",
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"@tailwindcss/webpack": "workspace:^"
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}
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}
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`,
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'webpack.config.js': js`
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let MiniCssExtractPlugin = require('mini-css-extract-plugin')
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module.exports = {
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output: {
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clean: true,
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},
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plugins: [new MiniCssExtractPlugin()],
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module: {
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rules: [
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{
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test: /.css$/i,
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use: [MiniCssExtractPlugin.loader, 'css-loader', '@tailwindcss/webpack'],
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},
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],
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},
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}
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`,
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'src/index.js': js`import './index.css'`,
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'src/index.html': html`
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<div class="flex"></div>
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`,
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'src/index.css': css`
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@import 'tailwindcss/theme';
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@import 'tailwindcss/utilities';
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`,
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},
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},
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async ({ fs, spawn, exec, expect }) => {
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// Generate the initial build so output CSS files exist on disk
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await exec('pnpm webpack --mode=development')
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let process = await spawn('pnpm webpack --mode=development --watch')
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await process.onStdout((m) => m.includes('compiled successfully in'))
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expect(await fs.dumpFiles('./dist/*.css')).toMatchInlineSnapshot(`
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"
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--- ./dist/main.css ---
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.flex {
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display: flex;
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}
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"
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`)
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// Add a new Tailwind class to the HTML file
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await fs.write('src/index.html', html`
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<div class="flex underline"></div>
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`)
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await process.onStdout((m) => m.includes('compiled successfully in'))
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expect(await fs.dumpFiles('./dist/*.css')).toMatchInlineSnapshot(`
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"
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--- ./dist/main.css ---
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.flex {
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display: flex;
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}
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.underline {
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text-decoration-line: underline;
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}
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"
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`)
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},
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)
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test(
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'@tailwindcss/webpack loader with @apply',
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{
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fs: {
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'package.json': json`
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{
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"main": "./src/index.js",
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"browser": "./src/index.js",
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"dependencies": {
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"css-loader": "^6",
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"webpack": "^5",
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"webpack-cli": "^5",
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"mini-css-extract-plugin": "^2",
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"tailwindcss": "workspace:^",
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"@tailwindcss/webpack": "workspace:^"
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}
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}
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`,
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'webpack.config.js': js`
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let MiniCssExtractPlugin = require('mini-css-extract-plugin')
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module.exports = {
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output: {
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clean: true,
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},
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plugins: [new MiniCssExtractPlugin()],
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module: {
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rules: [
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{
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test: /.css$/i,
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use: [MiniCssExtractPlugin.loader, 'css-loader', '@tailwindcss/webpack'],
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},
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],
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},
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}
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`,
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'src/index.js': js`import './index.css'`,
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'src/index.css': css`
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@import 'tailwindcss/theme';
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.btn {
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@apply flex items-center px-4 py-2 rounded-md;
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}
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`,
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},
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},
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async ({ fs, exec, expect }) => {
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await exec('pnpm webpack --mode=development')
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expect(await fs.dumpFiles('./dist/*.css')).toMatchInlineSnapshot(`
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"
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--- ./dist/main.css ---
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:root, :host {
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--spacing: 0.25rem;
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--radius-md: 0.375rem;
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}
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.btn {
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display: flex;
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align-items: center;
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border-radius: var(--radius-md);
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padding-inline: calc(var(--spacing) * 4);
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padding-block: calc(var(--spacing) * 2);
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}
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"
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`)
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},
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)
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test(
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'@tailwindcss/webpack loader with optimization',
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{
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fs: {
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'package.json': json`
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{
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"main": "./src/index.js",
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"browser": "./src/index.js",
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"dependencies": {
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"css-loader": "^6",
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"webpack": "^5",
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"webpack-cli": "^5",
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"mini-css-extract-plugin": "^2",
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"tailwindcss": "workspace:^",
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"@tailwindcss/webpack": "workspace:^"
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}
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}
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`,
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'webpack.config.js': js`
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let MiniCssExtractPlugin = require('mini-css-extract-plugin')
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module.exports = {
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output: {
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clean: true,
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},
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plugins: [new MiniCssExtractPlugin()],
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module: {
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rules: [
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{
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test: /.css$/i,
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use: [
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MiniCssExtractPlugin.loader,
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'css-loader',
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{
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loader: '@tailwindcss/webpack',
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options: {
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optimize: true,
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},
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},
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],
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},
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],
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},
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}
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`,
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'src/index.js': js`import './index.css'`,
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'src/index.html': html`
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<div class="flex"></div>
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`,
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'src/index.css': css`
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@import 'tailwindcss/theme';
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@import 'tailwindcss/utilities';
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`,
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},
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},
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async ({ fs, exec, expect }) => {
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await exec('pnpm webpack --mode=development')
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expect(await fs.dumpFiles('./dist/*.css')).toMatchInlineSnapshot(`
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"
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--- ./dist/main.css ---
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.flex{display:flex}
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"
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`)
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},
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)
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test(
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'@tailwindcss/webpack loader with CSS @import',
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{
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fs: {
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'package.json': json`
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{
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"main": "./src/index.js",
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"browser": "./src/index.js",
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"dependencies": {
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"css-loader": "^6",
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"webpack": "^5",
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"webpack-cli": "^5",
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"mini-css-extract-plugin": "^2",
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"tailwindcss": "workspace:^",
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"@tailwindcss/webpack": "workspace:^"
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}
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}
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`,
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'webpack.config.js': js`
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let MiniCssExtractPlugin = require('mini-css-extract-plugin')
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module.exports = {
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output: {
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clean: true,
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},
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plugins: [new MiniCssExtractPlugin()],
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module: {
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rules: [
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{
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test: /.css$/i,
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use: [MiniCssExtractPlugin.loader, 'css-loader', '@tailwindcss/webpack'],
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},
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],
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},
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}
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`,
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'src/index.js': js`import './index.css'`,
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'src/index.html': html`
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<div class="flex custom-util"></div>
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`,
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'src/index.css': css`
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@import './custom.css';
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@import 'tailwindcss/theme';
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@import 'tailwindcss/utilities';
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`,
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'src/custom.css': css`
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/**/
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@utility custom-util {
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color: var(--color-red-500);
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}
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`,
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},
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},
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async ({ fs, exec, expect }) => {
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await exec('pnpm webpack --mode=development')
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expect(await fs.dumpFiles('./dist/*.css')).toMatchInlineSnapshot(`
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"
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--- ./dist/main.css ---
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:root, :host {
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--color-red-500: oklch(63.7% 0.237 25.331);
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}
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.flex {
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display: flex;
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}
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.custom-util {
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color: var(--color-red-500);
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}
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"
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`)
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},
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)
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test(
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'@tailwindcss/webpack loader with @plugin',
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{
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fs: {
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'package.json': json`
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{
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"main": "./src/index.js",
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"browser": "./src/index.js",
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"dependencies": {
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"css-loader": "^6",
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"webpack": "^5",
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"webpack-cli": "^5",
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"mini-css-extract-plugin": "^2",
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"tailwindcss": "workspace:^",
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"@tailwindcss/webpack": "workspace:^"
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}
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}
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`,
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'webpack.config.js': js`
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let MiniCssExtractPlugin = require('mini-css-extract-plugin')
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module.exports = {
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output: {
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clean: true,
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},
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plugins: [new MiniCssExtractPlugin()],
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module: {
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rules: [
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{
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test: /.css$/i,
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use: [MiniCssExtractPlugin.loader, 'css-loader', '@tailwindcss/webpack'],
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},
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],
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},
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}
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`,
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'src/index.js': js`import './index.css'`,
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'src/index.html': html`
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<div class="custom-underline"></div>
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`,
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'src/index.css': css`
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@import 'tailwindcss/utilities';
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@plugin './plugin.js';
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`,
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'src/plugin.js': js`
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export default function ({ addUtilities }) {
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addUtilities({
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'.custom-underline': {
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'border-bottom': '1px solid green',
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},
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})
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}
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`,
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},
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},
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async ({ fs, exec, expect }) => {
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await exec('pnpm webpack --mode=development')
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expect(await fs.dumpFiles('./dist/*.css')).toMatchInlineSnapshot(`
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"
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--- ./dist/main.css ---
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.custom-underline {
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border-bottom: 1px solid green;
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}
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"
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`)
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},
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)
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